The invention relates to a photopolymer formulation comprising a polyol component, a polyisocyanate component, a writing monomer, and a photoinitiator, containing a coinitiator and a dye having the formula F An, where F stands for a cationic dye and An″ stands for an anion, wherein the dye having the formula F An comprises a water absorption of =5%. The invention further relates to a holographic medium, in particular in the form of a film, containing a photopolymer formulation according to the invention, to the use of such a medium for recording holograms, and to a special dye that can be used in the photopolymer formulation according to the invention.

The present disclosure concerns the design, formulations, preparations and optical properties of compounds of Formulas (I) and (VI):

(charged dye.sup.m+).sub.x.Math.(counterion.sup.n).sub.y.Math.(counterion receptor).sub.z(I) and

(charged dye.sup.m).sub.x.Math.(counterion.sup.n+).sub.y.Math.(counterion receptor).sub.z(VI).

The charged dye.sup.m+ is a cationic dye, counterion.sup.n is an anion, and counterion receptor is a binding ligand for the counterion.sup.n, wherein m, n, x and y are integers greater than or equal to 1, and products of x.Math.n and m.Math.y are identical for formula (I).

The charged dye.sup.m is a anionic dye, counterion.sup.n+ is a cation, and counterion receptor is a binding ligand for the counterion.sup.n+, wherein m, n, x and y are integers greater than or equal to 1, and products of x.Math.n and m.Math.y are identical for formula (VI).

The invention relates to cationic direct dyes of the formula I (1), wherein m and n are independently from each other 0 or 1, D is an aromatic or a cationic heteroaromatic group, which are further specified, K is an aromatic or heteroaromatic group, E.sub.1 and E.sub.2 are independently from each other CH or N, An is an anion and a is a number from 1 to 6 and R.sub.1 and R.sub.2 are independently from each other and further specified. The compounds show washfastness at hair-dying. ##STR00001##

The invention relates to cationic direct dyes of the formula I (1), wherein m and n are independently from each other 0 or 1, D is an aromatic or a cationic heteroaromatic group, which are further specified, K is an aromatic or heteroaromatic group, E.sub.1 and E.sub.2 are independently from each other CH or N, An is an anion and a is a number from 1 to 6 and R.sub.1 and R.sub.2 are independently from each other and further specified. The compounds show washfastness at hair-dying.

##STR00001##

The present disclosure concerns the design, formulations, preparations and optical properties of compounds of Formulas (I) and (VI):
(charged dye.sup.m+).sub.x.Math.(counterion.sup.n).sub.y.Math.(counterion receptor).sub.z(I) and
(charged dye.sup.m).sub.x.Math.(counterion.sup.n+).sub.y.Math.(counterion receptor).sub.z(VI). The charged dye.sup.m+ is a cationic dye, counterion.sup.n is an anion, and counterion receptor is a binding ligand for the counterion.sup.n, wherein m, n, x and y are integers greater than or equal to 1, and products of x.Math.n and m.Math.y are identical for formula (I). The charged dye.sup.m is a anionic dye, counterion.sup.n+ is a cation, and counterion receptor is a binding ligand for the counterion.sup.n+, wherein m, n, x and y are integers greater than or equal to 1, and products of x.Math.n and m.Math.y are identical for formula (VI).